A Pronghorn Success Story

by Norm Lowe

Two pronghorn antelope spotted on Bar T Bar Ranch in June.

Pronghorn antelope, which have been a dynamic part of the grasslands and woodlands of the Diablo Trust area for thousands of years, almost disappeared twenty years ago. Many experts studied the problem but couldn’t agree on the cause, which could include: too many roads, highways, and barb wire fences; an increase in woodlands cover giving predators the advantage; cattle and elk grazing, which reduces critical spring forb forage; changes in plant diversity due to desertification; increases in recreation activity and hunting pressures; and genetic weakening from interbreeding in small herd sizes. Diablo Trust, using its collaborative model, worked closely with the Arizona Game and Fish Department (AGFD) on several fronts to improve conditions. While livestock grazing in pastures was easily planned and managed to benefit antelope, elk numbers were very high and the elk stayed on critical land areas too long.

According to Rick Miller, retired AGFD wildlife specialist, hunting permitting was used to reduce elk by 50%. Rick help find and administer special grant funding to cooperate with the ranches to do massive clearing of invading juniper to open up grasslands and migration corridors. Diablo Trust coordinated with the Arizona Antelope Foundation to install smooth bottom wires at a raised height on fences. Radio collars were installed on a sampling of animals and it was learned there are two distinct herds, one which spends the whole year in the lower valley areas and one which summers on Anderson Mesa. Targeted coyote control was shown to also improve fawn survival.

To date, over 100,000 acres of grasslands have been restored in an antelope-friendly fashion. In the mid 1990s, an unsustainable average of only six fawns survived per 100 does. According to Tom McCall, current AGFD wildlife specialist for Region II, where the Diablo Trust ranches are located, though fawn survival did decrease some due to a dry spring season, now about 37 fawns survive per 100 does and total herd sizes are stable. Hunting quotas are conservative.

According to Tom Mackin, Diablo Trust’s wildlife chair and leading northern Arizona wildlife volunteer, Diablo Trust has been doing the right things to improve wildlife conditions. Waters are maintained well and the big black tire drinker troughs ensure year-round animal access to most areas. The Landowner Compact Agreement (see next page) also helps reduce off-road disturbances to animals and natural habitat. 

Watch our calendar for wildlife-themed Days on the Land to get large and small animal experts and wildlife groups out to visit key habitat areas. Contact our office if you are interested in wildlife oriented volunteer opportunities.